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Yu H, Basu S, Hallow KM. Cardiac and renal function interactions in heart failure with reduced ejection fraction: A mathematical modeling analysis. PLoS Comput Biol 2020; 16:e1008074. [PMID: 32804929 PMCID: PMC7451992 DOI: 10.1371/journal.pcbi.1008074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 08/27/2020] [Accepted: 06/18/2020] [Indexed: 01/10/2023] Open
Abstract
Congestive heart failure is characterized by suppressed cardiac output and arterial filling pressure, leading to renal retention of salt and water, contributing to further volume overload. Mathematical modeling provides a means to investigate the integrated function and dysfunction of heart and kidney in heart failure. This study updates our previously reported integrated model of cardiac and renal functions to account for the fluid exchange between the blood and interstitium across the capillary membrane, allowing the simulation of edema. A state of heart failure with reduced ejection fraction (HF-rEF) was then produced by altering cardiac parameters reflecting cardiac injury and cardiovascular disease, including heart contractility, myocyte hypertrophy, arterial stiffness, and systemic resistance. After matching baseline characteristics of the SOLVD clinical study, parameters governing rates of cardiac remodeling were calibrated to describe the progression of cardiac hemodynamic variables observed over one year in the placebo arm of the SOLVD clinical study. The model was then validated by reproducing improvements in cardiac function in the enalapril arm of SOLVD. The model was then applied to prospectively predict the response to the sodium-glucose co-transporter 2 (SGLT2) inhibitor dapagliflozin, which has been shown to reduce heart failure events in HF-rEF patients in the recent DAPAHF clinical trial by incompletely understood mechanisms. The simulations predict that dapagliflozin slows cardiac remodeling by reducing preload on the heart, and relieves congestion by clearing interstitial fluid without excessively reducing blood volume. This provides a quantitative mechanistic explanation for the observed benefits of SGLT2i in HF-rEF. The model also provides a tool for further investigation of heart failure drug therapies.
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Affiliation(s)
- Hongtao Yu
- School of Chemical, Materials, and Biomedical Engineering, University of Georgia, Athens, Georgia, United States of America
| | - Sanchita Basu
- School of Chemical, Materials, and Biomedical Engineering, University of Georgia, Athens, Georgia, United States of America
| | - K. Melissa Hallow
- School of Chemical, Materials, and Biomedical Engineering, University of Georgia, Athens, Georgia, United States of America
- Department of Epidemiology and Biostatistics, University of Georgia, Athens, Georgia, United States of America
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Abstract
AIM Influenza B-associated rhabdomyolysis (IBAR) is an infrequent and little-known complication of influenza B virus infection in children. Diagnosis is usually made based on clinical history, the presence of influenza in the community and detection of virus in nasopharyngeal specimens. The aim of this study was to describe the clinical and laboratory manifestations, complications and outcomes of IBAR in Taiwanese children. METHODS A retrospective analysis was conducted in patients aged < 17 years who had been diagnosed with IBAR at a university children's hospital in North Taiwan during 2000-2007. All children enrolled in the study had presented with rhabdomyolysis associated with laboratory-confirmed influenza B infections. Demographic data, clinical manifestations, complications and outcomes were included in the analysis. RESULTS Overall, 24 IBAR cases were analysed. IBAR typically occurred in school-aged children with a 7:3 male:female ratio. The mean age was 7.2 ± 1.9 years. Nearly 63% of cases occurred between the ages of 6 and 9 years. The median interval between the onset of influenza and onset of IBAR was 3.4 days (range, 1-14). The calf muscles were involved in all cases. Laboratory tests indicated a mean initial blood creatine kinase of 4212 U/L. The median time to clinical recovery was 5 days (range 1-24). No patient had renal failure. IBAR tends to occur mainly in winter and spring during influenza B outbreaks. IBAR sometimes induces some complications, and early detection and careful medical treatment are necessary. CONCLUSION The results of this study indicate that outcomes of IBAR are good with proper medical care.
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Affiliation(s)
- C-T Wu
- Division of Pediatric Emergency Medicine, Chang Gung Children's Hospital, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Tauyuan, Taiwan.
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Abstract
BACKGROUND This study was designed to determine the clinical characteristics of children infected with different strains of influenza B viruses isolated in southern Taiwan. The clinical features were compared with influenza A infection occurring in the same period. METHODS All children enrolled in the study had laboratory-confirmed infection with influenza A or B viruses. Influenza B speciation was performed by RNA extraction, cDNA synthesis, and amplification by polymerase chain reaction and sequencing. Demographic data, clinical findings, diagnoses, and outcomes were obtained. RESULTS During the study period, 163 strains of influenza A and 118 strains of influenza B were isolated. The Yamagata-like strains were most prevalent in 2001. New reassortant strains were identified since 2002 and became predominant in 2005 and 2006. Children with influenza B were more likely than those with influenza A to be diagnosed as upper respiratory tract infection, myositis, and gastroenteritis (P < 0.05). Children infected with Yamagata-like strains were more likely to develop lower respiratory tract infection (P < 0.05) and accounted for all cases of invasive disease. Children infected with the Victoria-like group had the longest hospital stays associated with severe bacterial superinfection. CONCLUSIONS Currently new reassortant influenza B viruses are the predominant strains circulating in southern Taiwan. There is considerable similarity of clinical features between influenza A and B in children. The Yamagata-like strains were associated with more invasive infections. Continuous influenza virus surveillance is essential particularly in Taiwan where pandemic strains tend to appear earlier than in other countries.
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Abstract
The NB protein of influenza B virus is thought to function as an ion channel and therefore would be expected to have an essential function in viral replication. Because direct evidence for its absolute requirement in the viral life cycle is lacking, we generated NB knockout viruses by reverse genetics and tested their growth properties both in vitro and in vivo. Mutants not expressing NB replicated as efficiently as the wild-type virus in cell culture, whereas in mice they showed restricted growth compared with findings for the wild-type virus. Thus, the NB protein is not essential for influenza B virus replication in cell culture but promotes efficient growth in mice.
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Affiliation(s)
- Masato Hatta
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Thomas JM, Stevens MP, Percy N, Barclay WS. Phosphorylation of the M2 protein of influenza A virus is not essential for virus viability. Virology 1998; 252:54-64. [PMID: 9875317 DOI: 10.1006/viro.1998.9384] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
M2 is a minor component of the influenza A virus envelope. The cytoplasmic tail of the M2 protein is posttranslationally modified in the infected cell by palmitylation and phosphorylation. The primary site for phosphorylation of the M2 cytoplasmic tail is serine 64, which is highly conserved yet not required for the activity of the M2 ion channel. Using an exogenous incorporation assay, we have shown that incorporation of M2 into virus particles is type-specific and does not require phosphorylation of the cytoplasmic tail. In addition, phosphorylation of the cytoplasmic tail is not required for the directional transport of M2 in polarized MDCK cells. Using a reverse genetics and reassortment procedure, we generated a virus (Ra) specifically mutated in segment 7 such that the M2 cytoplasmic tail could no longer be phosphorylated. The virus was found to grow as well as wild-type virus in tissue culture and in eggs, was stable on passage in these systems, and possessed no second-site mutations in the engineered RNA segment. In vivo Ra replicated in Balb/c mice at least as well as the parent strain A/WSN/33. These studies indicate that phosphorylation of the M2 cytoplasmic tail is not required for in vitro or in vivo replication of influenza A virus.
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Affiliation(s)
- J M Thomas
- School of Animal and Microbial Sciences, University of Reading, Whiteknights, UK
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Lamb RA, Pinto LH. Do Vpu and Vpr of human immunodeficiency virus type 1 and NB of influenza B virus have ion channel activities in the viral life cycles? Virology 1997; 229:1-11. [PMID: 9123850 DOI: 10.1006/viro.1997.8451] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- R A Lamb
- Howard Hughes Medical Institute, Northwestern University, Evanston, Illinois 60208-3500, USA.
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Abstract
Influenza virus infections continue to cause substantial morbidity and mortality with a worldwide social and economic impact. The past five years have seen dramatic advances in our understanding of viral replication, evolution, and antigenic variation. Genetic analyses have clarified relationships between human and animal influenza virus strains, demonstrating the potential for the appearance of new pandemic reassortants as hemagglutinin and neuraminidase genes are exchanged in an intermediate host. Clinical trials of candidate live attenuated influenza virus vaccines have shown the cold-adapted reassortants to be a promising alternative to the currently available inactivated virus preparations. Modern molecular techniques have allowed serious consideration of new approaches to the development of antiviral agents and vaccines as the functions of the viral genes and proteins are further elucidated. The development of techniques whereby the genes of influenza viruses can be specifically altered to investigate those functions will undoubtedly accelerate the pace at which our knowledge expands.
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Affiliation(s)
- M W Shaw
- Department of Epidemiology, University of Michigan, Ann Arbor 48109
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Abstract
This chapter discusses some observations concerning the natural occurrence and structural organization of polycistronic animal virus mRNAs, and the mechanisms by which they may be translated to yield two or more unique polypeptide products. In most polycistronic viral mRNAs, initiation of translation of both the 5’-proximal, upstream cistron and the internal, downstream cistron(s) likewise occurs at an AUG codon. Animal viruses encoding polycistronic mRNAs in which translation-initiation occurs alternatively at one or more AUG initiation sites, include members of several virus families that utilize a variety of different replication strategies as parts of their life cycles. They include: 1. viruses with DNA genomes and viruses with RNA genomes; 2. viruses with circular genomes and viruses with linear genomes; 3. viruses whose genomes are constituted by a single piece of nucleic acid, as well as viruses with segmented genomes; and 4. viruses that utilize the cell nucleus as the site for mRNA biogenesis, as well as viruses whose mRNA is synthesized in the cytoplasm. Furthermore, many different biochemical mechanisms may exist in animal cells to permit the expression of functionally polycistronic viral mRNAs.
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Polylactosaminoglycan modification of a small integral membrane glycoprotein, influenza B virus NB. Mol Cell Biol 1988. [PMID: 3367907 DOI: 10.1128/mcb.8.3.1186] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The structure of the carbohydrate components of NB, the small integral membrane glycoprotein of influenza B virus, was investigated. The carbohydrate chains of NB are processed from the high-mannose form (NB18) to a heterogeneous form of much higher molecular weight, designated NBp. Selection of this carbohydrate-containing form of NB with Datura stramonium lectin, its susceptibility to digestion by endo-beta-galactosidase, and determination of the size of NBp glycopeptides by gel filtration chromatography suggested that the increase in molecular weight is due to processing to polylactosaminoglycan. Investigation of the polypeptides produced by influenza B/Lee/40 virus infection of several cell types and another strain of influenza B virus suggested that the signal for modification to polylactosaminoglycan is contained in NB. Expression of mutants of NB lacking either one or both of the normal N-terminal sites of asparagine-linked glycosylation indicated that both carbohydrate chains are modified to contain polylactosaminoglycan. NBp and a small amount of unprocessed NB18 are expressed at the infected-cell surface, as determined by digestion of the surfaces of intact cells with various endoglycosidases. Unglycosylated NB, expressed either in influenza B virus-infected cells treated with tunicamycin or in cells expressing the NB mutant lacking both N-linked glycosylation sites, was expressed at the cell surface, indicating that NB does not require carbohydrate addition for transport.
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Williams MA, Lamb RA. Polylactosaminoglycan modification of a small integral membrane glycoprotein, influenza B virus NB. Mol Cell Biol 1988; 8:1186-96. [PMID: 3367907 PMCID: PMC363263 DOI: 10.1128/mcb.8.3.1186-1196.1988] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The structure of the carbohydrate components of NB, the small integral membrane glycoprotein of influenza B virus, was investigated. The carbohydrate chains of NB are processed from the high-mannose form (NB18) to a heterogeneous form of much higher molecular weight, designated NBp. Selection of this carbohydrate-containing form of NB with Datura stramonium lectin, its susceptibility to digestion by endo-beta-galactosidase, and determination of the size of NBp glycopeptides by gel filtration chromatography suggested that the increase in molecular weight is due to processing to polylactosaminoglycan. Investigation of the polypeptides produced by influenza B/Lee/40 virus infection of several cell types and another strain of influenza B virus suggested that the signal for modification to polylactosaminoglycan is contained in NB. Expression of mutants of NB lacking either one or both of the normal N-terminal sites of asparagine-linked glycosylation indicated that both carbohydrate chains are modified to contain polylactosaminoglycan. NBp and a small amount of unprocessed NB18 are expressed at the infected-cell surface, as determined by digestion of the surfaces of intact cells with various endoglycosidases. Unglycosylated NB, expressed either in influenza B virus-infected cells treated with tunicamycin or in cells expressing the NB mutant lacking both N-linked glycosylation sites, was expressed at the cell surface, indicating that NB does not require carbohydrate addition for transport.
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Affiliation(s)
- M A Williams
- Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208
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Determination of the orientation of an integral membrane protein and sites of glycosylation by oligonucleotide-directed mutagenesis: influenza B virus NB glycoprotein lacks a cleavable signal sequence and has an extracellular NH2-terminal region. Mol Cell Biol 1987. [PMID: 3025652 DOI: 10.1128/mcb.6.12.4317] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The membrane orientation of the NB protein of influenza B virus, a small (Mr, approximately 18,000) glycoprotein with a single internal hydrophobic domain, was investigated by biochemical and genetic means. Cell fractionation and protein solubility studies indicate NB is an integral membrane protein, and NB has been shown to be a dimer under nonreducing conditions. Treatment of infected-cell surfaces with proteinase K and endoglycosidase F and immunoprecipitation with a site-specific antibody suggests that the 18-amino-acid NH2-terminal region of NB is exposed at the cell surface. Oligonucleotide-directed mutagenesis to eliminate each of the four potential sites of N-linked glycosylation and expression of the mutant NB proteins in eucaryotic cells suggest that the two sites adjacent to the NH2 terminus are glycosylated. This provides further evidence that NB, which lacks a cleavable NH2-terminal signal sequence, has an exposed NH2 terminus at the cell surface.
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Servidei S, Miranda AF, Gamboa ET. Infectivity of influenza B virus in cultured human muscle. Acta Neuropathol 1987; 73:67-76. [PMID: 3300131 DOI: 10.1007/bf00695504] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Severe muscle symptoms, particularly in children, are frequently associated with influenza B virus infection. In this study we examined the effects of influenza B virus (Lee Strain) on cultured human muscle by light and electron microscopy (EM), immunofluorescence, hemadsorption and plaque assays. Muscle injury was also evaluated by the appearance of muscle-specific creatine kinase (CK) in the culture medium. By fluorescence immunocytochemistry viral antigen was demonstrated in muscle cell nuclei within 3 h postinoculation (p.i.) and in the cytoplasm at 6 h p.i. Membrane-associated viral antigen was seen at 16 h p.i., at which time budding influenza virus-like particles could be demonstrated by EM, both in myoblasts and multinucleated myotubes. At 16 h all cells were hemadsorption positive. Plaque assays showed peak virus production at 48 h (p.i.), at which time cytopathic effects (cell retraction, pycnosis and cytoplasmic vacuolization) were prominent and some cells detached from the substratum. Leakage of muscle-specific CK isozyme into the culture medium could be demonstrated as early as 6 h p.i. with peak enzyme activity around 40-48 h p.i. Cytopathic changes and virus production were observed both in myoblasts and myotubes indicating that both cell types are susceptible.
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Williams MA, Lamb RA. Determination of the orientation of an integral membrane protein and sites of glycosylation by oligonucleotide-directed mutagenesis: influenza B virus NB glycoprotein lacks a cleavable signal sequence and has an extracellular NH2-terminal region. Mol Cell Biol 1986; 6:4317-28. [PMID: 3025652 PMCID: PMC367213 DOI: 10.1128/mcb.6.12.4317-4328.1986] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The membrane orientation of the NB protein of influenza B virus, a small (Mr, approximately 18,000) glycoprotein with a single internal hydrophobic domain, was investigated by biochemical and genetic means. Cell fractionation and protein solubility studies indicate NB is an integral membrane protein, and NB has been shown to be a dimer under nonreducing conditions. Treatment of infected-cell surfaces with proteinase K and endoglycosidase F and immunoprecipitation with a site-specific antibody suggests that the 18-amino-acid NH2-terminal region of NB is exposed at the cell surface. Oligonucleotide-directed mutagenesis to eliminate each of the four potential sites of N-linked glycosylation and expression of the mutant NB proteins in eucaryotic cells suggest that the two sites adjacent to the NH2 terminus are glycosylated. This provides further evidence that NB, which lacks a cleavable NH2-terminal signal sequence, has an exposed NH2 terminus at the cell surface.
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Jacobs BL, Atwater JA, Munemitsu SM, Samuel CE. Biosynthesis of reovirus-specified polypeptides. The s1 mRNA synthesized in vivo is structurally and functionally indistinguishable from in vitro-synthesized s1 mRNA and encodes two polypeptides, sigma 1a and sigma 1bNS. Virology 1985; 147:9-18. [PMID: 2998074 DOI: 10.1016/0042-6822(85)90222-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The structural and functional properties of the reovirus serotype 1 (Lang strain) s1 mRNA were examined. Reovirus s-class mRNAs, synthesized either in vivo within infected mouse L cells or in vitro by chymotrypsin-derived cores of purified virions, were purified by filter-hybridization using cDNA clones of the S-class genome segments. S1 cDNA-selected mRNA encoded the synthesis of the Mr approximately 12,000 nonstructural polypeptide designated sigma 1bNS in addition to the well-established structural polypeptide sigma 1, now designated sigma 1a. The coding properties of in vivo- and in vitro-synthesized s1 mRNA were equivalent: both encoded sigma 1a and sigma 1bNS. Primer extension analysis of s1 mRNA revealed a single major 5' terminus for both in vivo- and in vitro-synthesized s1 mRNA. These results suggest that there is a single transcript of the reovirus S1 genome segment which is functionally dicistronic, and likely encodes both sigma 1a and sigma 1bNS.
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Hiebert SW, Paterson RG, Lamb RA. Identification and predicted sequence of a previously unrecognized small hydrophobic protein, SH, of the paramyxovirus simian virus 5. J Virol 1985; 55:744-51. [PMID: 4020965 PMCID: PMC255058 DOI: 10.1128/jvi.55.3.744-751.1985] [Citation(s) in RCA: 73] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A previously unrecognized gene (SH) has been identified on the virion RNA of the paramyxovirus simian virus 5 between the genes for the fusion protein and the hemagglutinin-neuraminidase. An SH mRNA of 292 nucleotides (plus polyadenylate residues), transcribed from the SH gene, has been identified. The SH mRNA contains a single open reading frame which encodes a polypeptide of 44 amino acids with a molecular weight of 5,012. The SH polypeptide is predicted to contain an extensive hydrophobic region. This protein has been identified in simian virus 5-infected cells, and it has been shown to be encoded by the SH mRNA by in vitro translation of size-fractionated mRNAs, hybrid-arrest translation, and hybrid-selection translation.
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Jacobs BL, Samuel CE. Biosynthesis of reovirus-specified polypeptides: the reovirus s1 mRNA encodes two primary translation products. Virology 1985; 143:63-74. [PMID: 4060584 DOI: 10.1016/0042-6822(85)90097-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Reovirus serotypes 1 (Lang strain) and 3 (Dearing strain) code for a hitherto unrecognized low-molecular-weight polypeptide of Mr approximately 12,000. This polypeptide (p12) was synthesized in vitro in L-cell-free protein synthesizing systems programmed with either reovirus serotype 1 mRNA, reovirus serotype 3 mRNA, or with denatured reovirus genome double-stranded RNA, and in vivo in L-cell cultures infected with either reovirus serotype. The synthesis of p12 in vivo was insensitive to actinomycin D, and occurred at similar times after infection as the previously identified reovirus encoded lambda, mu, and sigma polypeptides. Pulse-chase experiments in vivo, and the relative kinetics of synthesis of p12 in vitro, indicate that it is a primary translation product. Fractionation of reovirus mRNAs by velocity sedimentation and translation of separated mRNAs in vitro suggests that p12 is coded for by the s1 mRNA, which also codes for the previously recognized sigma 1 polypeptide. Synthesis of both p12 and sigma 1 in vitro in L-cell-free protein synthesizing systems programmed with denatured reovirus genome double-stranded RNA also suggests that these two polypeptides can be coded by the same mRNA species. The Mr approximately 12,000 polypeptide was not a detectable structural component of purified virions, and antiserum prepared against purified reovirions did not immunoprecipitate p12. It is proposed that the Mr approximately 12,000 polypeptide encoded by the S1 genome segment be designated sigma 1bNS, and that the polypeptide previously designated sigma 1 be renamed sigma 1a.
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